PROJECT ABSTRACT/SUMMARY Early life adversities have been associated with a variety of negative outcomes, including risk for mild cognitive impairment (MCI) and Alzheimer's disease (AD). However, knowledge about the relationship between childhood adversities ? particularly child abuse and neglect ? and cognitive decline and functioning in adulthood is limited. Existing research relies heavily on cross-sectional studies and retrospective self-reports of childhood maltreatment. While the results of these studies are suggestive, conclusive evidence linking verified child maltreatment and cognitive decline and AD does not exist, a significant gap in the literature. Reliance on retrospective self-reports, particularly with an aging or aged population, leads to questions about the reliability and validity of that information. The proposed research seeks to: (1) determine whether cognitive decline is more rapid in adults with documented maltreatment histories and whether they are at increased risk for MCI and AD; (2) examine two hypothesized pathways from child maltreatment to increased risk for MCI/AD through (a) physical health and psychosocial risk factors and (b) biological markers; (3) examine potential modifiable and non-modifiable risk factors that may protect maltreated children from risk for MCI/AD; and (4) compare risk for MCI/AD using both prospective and retrospective reports of child maltreatment and determine the reliability and validity of retrospective reports in an aging sample. Capitalizing on a unique prospective longitudinal study, the proposed research will use existing and newly collected data from a large sample of well-characterized, high-risk individuals that have been studied for over 30 years. This research has a number of important methodological advantages that overcome many of the limitations of previous research; (1) long term follow-up (estimated mean age 59 in 2020); (2) documented cases of child abuse and neglect; (3) a control group of children who were matched to the documented cases on the basis of age, sex, race/ethnicity, and approximate family social class at the time of the childhood abuse and neglect; (4) high rates of known risk factors for MCI/AD in both groups; (5) prospective longitudinal design that permits disentangling of issues of etiology and temporal sequence; (6) a diverse sample, including males, females, Blacks, and Whites; (7) participants and interviewers have been blinded to the purpose of the study, avoiding issues of bias; and (8) data on mediators has already been collected over several time points. The new data collection will include a neuropsychological battery using components of the NIH toolbox and NACC Uniform Data Set, a blood draw to determine APOE ?4 allele, epigenetic age, telomere length and immune function, assessment of attitudes towards aging and re-assessment of previous indicators, and retrospective self-reports of child maltreatment. The proposed research is more cost effective and feasible than designing a new prospective longitudinal study with these elements. This study will also generate a data archive that would be available for collaborative investigations of the effects of child maltreatment on cognitive decline and risk for MCI and AD.